Carburetor



Nov. 17, 1931. R. F. BRACKE ET AL 1,831,840

I CARBURETOR Filed May 17, 1929 2 Sheets-Sheet l foberijjfaaka C'arZ Z0, 5,0051

NOV. 17, 1931. BRACKE ET AL 1,831,840

CARBURETOR Filed May 1'7, 1929 2 Sheets-Sheet 2 flzugyzwrsx jfoer'i flflraczfe ('arZ 5,00%

Patented Nov. 17, 1931 UNITED STATES PATENT OFFICE ROBERT F. IBRAOKE AND CARL W. SPOHR, OF CHICAGO, ILLINOIS, ASSIGNOBS TO CURTIS B. CAMP, TRUSTEE, 0F GLENCOE, ILLINOIS CARBURETOR Application filed May 17,

Our invention relates to improvement in carburetors and more particularly carburewith such a carburetor, or during the immediate increase in speed of the vehicle while running, is intended to supply sufiicient fuel to momentarily meet engine demand so as to quickly bring the engine up to the desired speed without causing the engine to cough and suffer loss of power.

Up to the present time the accelerating mechanism employed in carburetors is dependent in operation upon the increase in opening movement of the fuel mixture throttle valve. It is a common practice to mechanically interconnect the shaft of the throttle valve with a piston, diaphragm or other pressure producing device which moves with the throttle valve to momentarily cause an additional flow of fuel into the induction chamber, either through the principal fuel nozzle or an auxiliary fuel nozzle provided for that purpose.

It is thus apparent that although such accelerating devices are intended to meet engine demand during the immediate advance in engine speed, in reality the additional quantity of fuel supplied to the induction chamber by the accelerating mechanism bears no direct relation to the actual engine demand, but is arbitrarily fixed by the degree and speed with which the carburetor throttle valve is advanced toward open or full open throttle position.

It is further evident that in the present type of carburetors as described, no accelerating charge is supplied to meet engine demand at increase in engine load with its attendant fall in manifold depression where unaccompanied by manual advance in throttle position. Such a condition arises where the vehicle arrives at up-grade changes in road level or where the nature of the road offers varying resistance in traction.

An object of our present invention is to 1929. Serial in. 363,802.

provide the improved carburetor of the type described. q

Another object is to provide a carburetor embodying means for supplying an additional charge of fuel to its inductionchamber during acceleration, which functions automatically and which is not directly dependent .in operation upon changes in the throttle valve position.

A further object is to provide a carburetor wherein an accelerating charge or fuel is automatically supplied to the induction chamber in proper proportion to directly meet increased engine demand, and which is entirely dependent in operation upon such increase in engine demand with its attendant decrease in manifold depression.

Another object is to provide a carburetor of the type described wherein the accelerating mechanism is unusually stable in its operation.

A further object is to provide an accelerating mechanism of the type herein described which may be embodied with equal success in operation in either the fuel lift or gravity feed type of carburetor.

Other objects and advantages will hereinafterappear.

Our invention will be explained as embodied in a vacuum feed carburetor of the fuel lift type as illustrated in the accompanying drawings, wherein Fig. 1 is a schematic sectional view of the carburetor;

Fig. 2 is a fragmentary sectional view of the mechanism illustrated in Fig. 1, showing the accelerating mechanism as it appears during the accelerating period; and

Fig. 3 is a sectional view of the motor vehicle equipped with our improved carburetor.

The carburetor illustrated in the drawings is of the fuel lift vacuum feed type and its use dispenses with the so-called vacuum tank or mechanical fuel lifting devices. Briefly, the carburetor comprises an induction chamber 1 having its throat 2 adapted for communication with the intake manifold mitted to the induction chamber 1 must pass, communicates with the induction chamber through an air valve 4. This air valve is normally maintained in closed position by a spring 5 which yields upon the creation of a depression in the chamber 1 as the valve 4 is caused to rise from its seat by atmospheric pressure. A dash-pot piston 6 is carried by the lower end of the valve 4 and is confined within an air dash-pot 7 formed in the body of the carburetor. The normal function of this dash-pot is to stabilize the opening and closing movement of the valve 4. A throttle valve 8 of the butterfly type is disposed in the throat of the induction chamber and comprises means for controlling the flow of fuel mixture from the induction chamber into the manifold of the engine.

Fuel is drawn upwardly from the fuel tank F at its low level to the induction chamber 1 by means of a Venturi tube fuel nozzle 10 which extends through the wall of the induction chamber 1. The construction of the Venturi tube nozzle 10 has been well established in the art and is known for its suction multiplying properties, i. e., suction at the throat 11 of the Venturi tube is greater than that suction to which the Venturi tube is subjected at its delivery 12 during the induction of air therethrough. The depression in the induction chamber 1 during operation of the carburetor is maintained substantially constant because of the air valve 4 and the degree of depression is such as to always assure depression at the throat of the Venturi tube 10 suflicient to lift fuel from the tank F to the throat of the venturi through chamber 15, where it is united with the air stream passing through the venturi and discharged into the induction chamber in the form of a inely atomized and vaporous mixture of rich uel. Means for re ulating the quantity of fuel so supplied to the throat of the Venturi tube 10 is provided in a fuel valve 16, which is operated by a flexible diaphragm 17 subjected to atmospheric pressure upon its upper side and to venturi throat pressure on its lower side. This diaphragm bears directly against the valve 16, causing the valve to open andadmit fuel to the throat 11 of the venturi through a fuel passage 18. As fuel' is supplied to the throat 11 to relieve the throat depression, the diaphragm 17 functions to hold the valve 16 in the proper position so that fuel is supplied at all times to the Venturi tube in proper proportion. As a further control of the quantity of fuel passing to the Venturi tube 11 during low and normal speeds, an economized valve 20 is provided which, when closed as shown invFig. 1, restricts the fuel passage 18, thus decreasing the quantity of fuel normally available to the Venturi tube. At higher speeds, however, this valve 20 is moved downwardly by engagement of a cam 21 therewith carried upon the shaft 22 of the throttle valve 8 to cause the economizer valve to move from its seat and permit maximum passage of fuel through the fuel passage 18.

The carburetor as described in the foregoing paragraphs comprises structure known in the art.

Our invention relates to an accelerating mechanism embodied in the foregoing described structure and cooperating therewith to supply additional quantities of fuel to the fuel venturi 10 at such times as when the proper amount of fuel cannot be otherwise supplied to the induction chamber because of a sudden decrease in manifold depression and hence induction chamber depression.

This sudden decrease in induction chamber depression causes the velocity of air passing through the fuel Venturi nozzle to drop and the fuel in the fuel passage passing to the throat of the nozzle has a tendency to fall back and resist normal flow to the nozzle at the lower induction chamber depression. The result of this condition unless remedied by an accelerating charge device is a short period of extreme leanness of mixture accompanied by unsatisfactory, sluggish engine operation.

With reference to Fig. 1, our improved accelerating mechanism consis s of automatic means for momentarily moving the air valve 4 toward closed position upon sudden decrease in engine manifold depression, thus momentarily increasing induction chamber depression, to cause a relatively greater supply of fuel to discharge into the induction chamber to meet engine demand for acceleration.

This mechanism comprises a closed air chamber 30 having a cylinder 31 formed therein with its lower end open. An air tube 32' extends from a point near the mouth of the cylinder 31 upwardly to and communicating with the throttle bore 2 of the induction chamber 1 above the throttle valve 8 as shown at 33. The air passage formed by the tube 32 is thus always subjected to en gine manifold depression.

A piston 35 having a long upwardly extending skirt 36 is loosely mounted within the cylinder 31 so that air may bleed past the piston through the air tube 32 to normally establish a depression within the chamber- 30 equivalent to engine manifold depression. An air valve 34 is carried by the lower end of the piston 35 and is disposed within a valve chamber 37. A spring 38 normally closes the valve against its seat 39 thus shutting ofi communication between the chambers 30 and 37 The spring also maintains the piston 35 in an elevated position as shown in Fig. 1.

An air duct 40 interconnects the valve chamber 37 and the air dash pot 7 beneath the dash pot piston 6 so that when the valve 34 is opened the depression in chamber 30 is communicated to the space beneath the dash pot piston 6. Normally the dash pot 7 is maintained at atmospheric pressure both above and below its piston because of the bleeding of air past the loosely fitting stem of the air valve 4.

In operation the quantity of fuel mixture supplied by the carburetor to the engine during normal operation is controlled by manual manipulation of the throttle valve 8 which is actuated by the drivers foot in a manner known to all motorists.- The throttle valve controls the quantity of air which may enter the induction chamber through the secondary air passage 3 and-hence the elevation of the air valve 4 which works against the spring 5 to maintain the induction chamber depression substantially constant.

The engine intake manifold suction is communicated to the air chamber 30 through the air tube 32 and that chamber is maintained constantly at the same depression as the manifold because of the communication around the loosely fitting piston 35.

Normally the valve chamber 37 and the air-dash pot 7 above and below the dash pot piston 6 is maintained at atmospheric pressure.

Let us assume that the engine is runnin at a constant speed and that the manlfol depression is equivalent to 16 inches of mercury as read from a manometer tube. Thls depression induces a predetermined depression in the induction chamber which is maintained substantially constant by the air valve 4. A certain quantity of fuel under these conditions is delivered to the throat of the Venturi nozzle 10 where it unites with the primary air stream passing through the venturi to produce a suit-able rlch vaporized mixture for discharge into the induction chamber and ultimately into the engine manifold. The air chamber 30 isunder a depreslent to 4 inches of mercury. There will thus be a difi'erential in depression of 4 inches between the chamber 30 and the cylinder 31; which is suflicient to cause the piston 35 to move downwardly against the spring 38 thus opening the valve 34 as shown in Figure 2.

The opening of the valve 34 permits the communication of the higher depression in the chamber 30 to the dash pot 7 beneath the dash pot piston 6. As this occurs the dash pot piston will be forced downwardly caus- 4 will immediately build up a higher depression in the induction chamber 1 than existed immediately upon the opening of the throttle valve 8 and will thus induce an increased flow of fuel to the fuel nozzle 10, thus providing adequate and properly proportioned accelerating charge.

This same operation of the mechanism not only occurs where the throttle valve 8 is opened as in manual acceleration from a given speed to a higher speed but at such times as when the vehicle encounters increased traction resistance and the speed of the engine is suddenly lowered, thus causing the manifold depression to fall. Carburetors of the type known today with accelerating devices depending upon throttle movement do not perform this useful and highly important accelerating function under such conditions.

It is also apparent that at all times the quantity of the accelerating charge must bear a fixed relationship to the fall in manifold depression as well as the element of. time during which the fall takes place. Obviously if the fallin manifold depression occurs slowly the accelerating mechanism will not function for in such a case it is not necessary that it shall functionas the condition of stability is maintained throughout the change. It is only such conditions as heretofore stated where the change occurs in so short .a time that the carburetor may not remain stable that the accelerating mecha nism becomes an important and vital element of the carburetor and necessary to efiicient and smooth engine operation.

Having thus described our invention what we claim as new and desire to secure by United States Letters Patent isas follows: 1. vIn a carburetor of the type wherein fuel is delivered to the induction chamber thereof by induction chamber depression, means associated with said chamber and governed by the depression in the intake manifold of an internal combustion engine for maintaining the depression in said chamber substantially constant and other means operable upon a sudden decrease in engine manifoldvdepression for momentarily effecting said first.

means for momentarily increasing induction chamber depression, thereby roviding increased fuel discharge for acce eration.

2. In a carburetor of the type wherein fuel is delivered to the induction chamber thereof by induction chamber depression, means associated with said chamber and governed by the depression in the intake manifold of an internal combustion en ine for maintaining the depression in said 0 amber substantially constant and other means operable by atmosproviding increased fuel discharge for acceleration.

- 3. In a carburetor of the type wherein fuel is delivered to its induction-chamber by induction chamber depression, an air valve associated with said chamber and governed by the depression in the intake manifold of an internal combustion engine for maintaining the depression in said induction chamber sub 'stantially constant and means operable sole- I? by a sudden decrease in engine manifold epression for momentarily moving the air valve to increase induction chamber depres-.

sion.

4. In a carburetor, a fuel induction chamber adapted for communication with the intake manifold of an internal combustion engine, an air valve associated with said chamber and governed by the depression in the intake manifold of the engine for controlling the passage of air into the induction chamber, a fuel nozzle for discharging fuel into the induction chamber-dependent in operation upon induction chamber depression, and automatic means for' momentarily moving said air valve toward closed position upon a sudden decrease in en ine manifold depression whereby an acceIerating charge of fuel may be supplied to the induction chamber.

5. In a carburetor of the type wherein fuel is delivered to its induction chamber by induction chamber depression, a spring gzessed air valve associated with said chamr and governed by the depression in the intake manifold of the engine for maintainin the depression in said induction chamber su stantially constant, a throttle valve for controlling the assage of fuel mixture from the induction c amber, and means operable by 'a sudden decrease in engine manifold de .pression for momentarily moving the air valve toward closed position, said means being entirely independent of fuel mixture throttle position.

6. In a carburetor, a fuel induction chamber adapted for communication with the intake manifold of an internal combustion engine, an air valve associated with said inducanism associated with said movable means for normally closing said passage, said movble means effective upon a sudden decrease in manifold depression to operate said valve mechanism and open said passage and subjecting said dash pot to said chamber depression for momentarily movin said air valve toward closed position where y a sudden accelerating charge of fuel is supplied to the induction cham er.

7. In a carburetor wherein fuel is supplied to the induction chamber of the carburetor by induction chamber depression, a spring pressed valve associated with said induction chamber for maintaining the induction chamber depression substantially constant, a dash pot and a piston associated with said air valve, a throttle valve for controlling the passage of fuel mixture to the intake manifold of an internal combustion engine,anormally closed air chamber, a cylinder having one end communicating with said air chamber, a passage interconnecting the cylinder and the induction chamber above said throttle valve to maintain said air'chamber and cylinder at engine manifold depression, a piston loosely fitted within said cylinder, a normally closed passage connecting said chamber with said dash pot and means controlled by said piston upon movement of the same for opening said passage to connect said air chamber with said dash pot and effective to cause said air valve to momentarily move toward closed position under the influence of a sudden fall of manifold depression.

' In witness whereof, we hereunto subscribe our names this 3rd day of May, 1929.

ROBERT F. BRACKE. CARL W. SPOHR.

tion chamber for controlling the passage of v air into the induction chamber, a dash pot and a. piston associated with said air valve, a fuel nozzle for discharging fuel into the induction chamber, dependentin operation upon induction chamberdepression, a chamber under constant subjection to engine manifold depression, movable means associated with said chamber operable upon a sudden decrease in engine manifold depression in said chamber, a assa'ge connecting said chamber and said ash pot and valve mech- 

